Merge branch 'siri/stdlib/hanging-restart-loop/OTP-9549' into maint

* siri/stdlib/hanging-restart-loop/OTP-9549:
  Leave control back to gen_server during supervisor's restart loop

1 files changed, 45 insertions, 0 deletions

diff --git a/lib/stdlib/test/supervisor_deadlock.erl b/lib/stdlib/test/supervisor_deadlock.erl
new file mode 100644
index 0000000000..288547a972
--- /dev/null
+++ b/lib/stdlib/test/supervisor_deadlock.erl
@@ -0,0 +1,45 @@
+-module(supervisor_deadlock).
+-compile(export_all).
+
+
+%%%-----------------------------------------------------------------
+%%% gen_server callbacks
+init([child]) ->
+    case ets:lookup(supervisor_deadlock,fail_start) of
+        [{fail_start, false}] ->
+            %% we must not fail on the first init, otherwise supervisor
+            %% terminates immediately
+            {ok, []};
+        [{fail_start, true}] ->
+	    %% Restart frequency is MaxR=8, MaxT=10, so this will
+	    %% ensure that restart intensity is not reached -> restart
+	    %% loop
+            timer:sleep(2000), % NOTE: this could be a gen_server call timeout
+
+            {stop, error}
+     end.
+
+handle_call(_Req, _From, State) ->
+    {reply, ok, State}.
+
+%% Force a restart
+handle_cast(restart, State) ->
+    {stop, error, State}.
+
+handle_info(_Msg, State) ->
+    {noreply, State}.
+
+terminate(_Reason, _State) ->
+    ok.
+
+code_change(_OldVsn, State, _Extra) ->
+    {ok, State}.
+
+
+%%%-----------------------------------------------------------------
+%%% Start child
+start_child() ->
+    gen_server:start_link({local, ?MODULE}, ?MODULE, [child], []).
+
+restart_child() ->
+    gen_server:cast(supervisor_deadlock, restart).